Automatic sliding door system

ABSTRACT

An automatic sliding door system comprising a door frame having a header constituting a housing, a door carrier provided in said housing and projecting downwardly through an elongated opening therein, a door suspended from said door carrier, a prime mover in said housing, a first gear train connecting said prime mover to an operating sprocket, an idler sprocket, belt members extending about said sprockets and connected to said door carrier for effecting traverse of said housing by said door carrier for sliding the door to and from open position. A spring stressed during door opening operation and a second gear train connecting said spring and said operating sprocket for causing the door carrier to restore the door to closed condition. Circuit controlling components are provided for causing two-speed dooropening and door-closing.

United States Patent 1191 1111 3, Catlett 1451 Sept. 10, 1974 AUTOMATICSLIDING DOOR SYSTEM Primary ExaminerKenneth Downey [75] Inventor. JohnC. Catlett, Elm Grove, Wis. Attorney, g or Firm Ralph w Kalish [73]Assignee: Gyro Tech Incorporated, Greendale,

57 ABSTRACT Filedi 1973 An automatic sliding door system comprising adoor [21] Appl' No; 346,476 frame having a header constituting ahousing, a door carrier provlded 1n said housing and projectingdownwardly through an elongated opening therein, a door U-S. 18,uspended from aid door carrier a prime mover in 49/139 49/327 saidhousing, a first gear train connecting said prime [5 mover to anperating procket an idler procket [58] Field of Search 49/116-118,members extending about Said Sprockets and Cam 49/123, 110, 141,138,327, 332, 360, 370, nected to said door carrier for effectingtraverse of 379, 139, 386, 29, 30, 2 274 said housing by said doorcarrier for sliding the door to and from open position. A springstressed during References Clted door opening operation and a secondgear train con- UNITED STATES PATENTS necting said spring and saidoperating sprocket for 580,370 4/1897 Canfield 49/30 Causing the doorcarrier to restore the door 10 Closed 2,653,022 9/1953 Armstrong 49/118x condition. Circuit controlling components are pro- 3,172,65l 3/1965Wilson 49/360 vided for causing two-speed door-opening and door-3.354.581 11/1967 Dimmitt et a1 49/327 X closing, 3,406,484 10 1968Atkey et al. 49/138 X 3,468,061 9/1969 Ozaki 49/360 11 Clalms, 20Drawlng Flgures Hmmsav 1 mm sum 2 or 9 FIG. 3

PAIENIED w x 0 1914 SEE] 8 (if 9 AUTOMATIC SLIDING DOOR SYSTEMBACKGROUND AND SUMMARY OF THE INVENTION vide an automatic sliding doorsystem which is substantially self-contained, embodying a power systemand motion transmission means requiring connection to a convenientlylocated source of electrical energy and actuating switch means foroperation.

It is another object of the present invention to provide an automaticsliding door system which incorporates simple electro-mechanicaloperating means and thus obviates the utilization of gases or liquids inthe transmission and operation of the door, thereby conducing to economyand reliability in use.

It is a further object of the present invention to provide an automaticsliding door system which effects door closure under release ofmechanical energy stored during door operation to thereby enhance thesafety of door closing; rendering the door amenable to manually impelledswinging action in the event of power failure, as well as to obviateutilization of door edge switches as may be found in currentconstructions.

It is a still further object of the present invention to provide anautomatic sliding door system which embodies novel control means forcausing variation in the speeds of door opening and door closingmovements for promoting both safety and relatively repair-free longevityof use.

It is another object of the present invention to provide an automaticsliding door system which is readily adapted for doors of the doubleleaf or the single leaf type and which systems are particularly amenableto presentation in attractive, ornamental design.

It is a still further object of the present invention to provide asystem of the character states which is constituted of relatively fewcomponents, all of which are of durable, wear-resistant construction;and which system incorporates easily manipulated means for appropriatelyadjusting components to assure of effective operation of the systemwithout requiring the customary dismantling procedure with attendantdown-time.

It is another object of the present invention to provide a system of thecharacter stated which is economical in construction, as well as ininstallation, and which requires the very minimum in maintenance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of asliding door system constructed in accordance with and embodying thepresent invention, illustrating a door of the double leaf type.

FIG. 2 is a view taken substantially along the line 22 of FIG. 1.

FIG. 3 is an elevational view of a sliding door system constructed inaccordance with and embodying the present invention but illustrating adoor of the single leaf type.

FIG. 4 is a view taken along the line 4-4 of FIG. 3.

FIG. 5 is a fragmentary elevational view of the header with the coverpanel removed; this view being taken as indicated by the arrow in FIG.1.

FIG. 6 is a vertical transverse sectional view taken along the line 66of FIG. 1.

FIG. 7 is a vertical transverse sectional view taken along the line 77of FIG. 6.

FIG. 8 is a horizontal transverse sectional view taken on the line 88 ofFIG. 1.

FIG. 9 is a horizontal view, partially in section, taken on the line 9-9of FIG. 5.

FIG. 10 is a fragmentary perspective view illustrating one of the doorleafs in openly swung condition.

FIG. 11 is a horizontal transverse sectional view taken on the line lll1of FIG. 10.

FIG. 12 is a schematic view of the belt and door carrier assembly.

FIG. 13 is a vertical transverse sectional view taken on the line l313of FIG. 5.

FIG. 14 is a vertical transverse sectional view taken on the line l414of FIG. 5.

FIG. 15 is a vertical view taken on the line 15-l5 of FIG. 14.

FIG. 16 is a vertical transverse sectional view taken on the line16l6'of FIG. 9.

FIG. 17 is a vertical view taken on the line l7l7 of FIG. 9.

FIG. 18 is a fragmentary vertical sectional view taken on the line l818of FIG. 8.

FIG. 19 is a view taken as indicated by the line 19 in FIG. 1.

FIG. 20 is a horizontal transverse sectional view taken on the line20-20 of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now by referencecharacters to the drawings which illustrate the preferred embodiment ofthe present invention, A designates generally an automatic sliding doorsystem which may be of the double leaf type, in comprising a pair ofcooperative, vertically disposed, horizontally aligned sliding doors1,1, adapted for edge-to-edge abutment in flush arrangement, when closed(see FIG. 1), and, hence, being movable away from each other for dooropening. As illustrated in FIGS. 3 and 4, the system of the presentinvention may also be only of the single leaf type having but oneslideable door 101 which would thus move toward and away from a jamb 102during closing and opening operation. However, for purposes ofexposition herein, the double leaf type will be described, but with therecognition that the present invention is equally adaptable for a singleleaf door.

Doors 1,1 are, accordingly, designed for closure of an opening 2provided within an entrance structure, in-

dicated generally 3, located within a wall opening; said structure 3incorporates spaced-apart vertical jambs 4,4, as fabricated of extrudedmetal stock, and with portions, as indicated by dotted lines, beingreceivable within the wall structure; there being a header 5 extendingtransversely of the opening 2 being suitably supported upon the upperends of jambs 4,4 and affixed to the structure overhead (not shown).Header 5, which is also fabricated of sheet metal, constitutes a housing6 with there being a removable cover paneling, indicated 6; for readyaccess to the interior of housing 6. Frame 3 also includes so-calledscreens 7,7 which are coplanar and the inner margins of which define theedges of opening 2. Each screen 7,7 is suitably engaged to header 5 (seeFIG. 6) as well as to the proximate jambs 4,4 and with there being abottom rail 9,9 and marginal verticals, as at 10,10, parallel to jambs4,4' and constituting the borders of opening 2. As may best be seen inFIG. 2, screens 7,7 are presented within a plane parallel to the planeof movement of doors 1,1' so that the latter in moving into closedcondition will travel into substantially registering relationship withthe related screen 7,7; it being recognized that the width of header 5is greater than the combined thickness of the related screens and doors(see FIG. 6), so that the same will, as shown below, accommodate thedoor operating components, as well as provide a suitable finish to thestructure 3. It is to be recognized that although screens 7,7 are shownas comprising transparent panels 8,8, the same could be of solid opaquematerials, such as wood and the like, if desired, for decorativepurposes.

In actual practice, entrance structure 3 will be presented with relationto the adjacent wall so that screens 7,7 will be located on what mightbe considered the outer side of such wall. Consequently, the view inFIG. 1 may be considered from the inside of said structure 3.

Each door 1,1 comprises vertical rails 11,12 and upper and lower rails13,14 respectively, which are desirably formed of extruded metal andadapted to support a transparent panel 15, as of glass.

As shown in the drawings, door rails 11 are of twopart charactercomprising a support component 16 and a companion component 17 with thesame being as by spaced hinges 18; and with the upper rail 13 being alsoof two-part construction having a top and bottom cooperating components19,20; said top component 19 being rigid at its ends with the adjacentsupport component 16. This particular construction of the stated doorleaves is for the purpose of permitting swinging of door leaves 1,1, asindicated in phantom lines in FIG. 2, under so-called panic or emergencyconditions. This capability will be discussed more fully hereinbelowbut, however, during the exposition of the slideable operation of doors,1,1 the referred to door rails will be considered unitary for simplicitypurposes.

Doors 1,1 are provided with overhead suspension and there being meansfor automatically sliding said doors 1,1 between open and closedposition through actuation of a conveniently located switch or othercontrol, such as, for example, floor switch mats, photoelectric cells,sonic switches, wall switches, remote switching systems and the like, sothat door operation does not require any conscious manipulation by doorusers.

Referring now to FIGS. 5-9, inclusive, it will be seen that there isprovided within header housing 6 a compact, self-contained power systemwhich obviates the requirement for remotely located equipment for dooroperation other than a customary source of electrical energy, as 1 15volt A.C., and the switching or actuation devices as above indicated.

Said power system incorporates a motor M, as of the direct current,permanent magnet-type, having a drive shaft 21 receivable within a gearbox B for connection by means of a gear train G, to be describedhereinbelow, to a shaft 22, whose axis extends transversely of housing6, upon an outwardly extending end of which is mounted an operatorsprocket 23, about which latter extends a transmission belt 24, asfabricated of molded rubber, and having upper and lower courses 25,25progressing in a direction lengthwise of housing 6 proximate the upperand lower walls thereof. At its end extremity upper course 25 of belt 24is fixed to a boss 26 formed at the proximate upper end, as at 27, of adoor carrier 28 disposed above, and secured to, the upper rail 13 ofdoor 1. The lower course 25 of belt 24, at its normally free end, issecured to the adjacent lower end portion, as at 29, of a door carrier30 disposed above, and secured to, the upper rail 13 of door 1. Theopposite end of door carrier 30 in its lower portion, as at 31, is fixedto the end of the lower course 32 of a transmission or timing belt 33,of the same construction as belt 24, which lower course 32 proceeds in adirection lengthwise of header housing 6 for engagement about theperiphery of an idler sprocket 34, of like construction as operatorsprocket 23, and located at the opposite end of housing 6 therefrom;said belt 33 having an upper course 35 which at its free end is securedrigidly to a boss 36 extending upwardly from the adjacent end portion ofdoor carrier 28 (see FIG. 5).

FIG. 12 illustrates schematically the sprocket wheel belt and doorcarrier arrangement and by reference thereto it will be seen that uponrotation of operator sprocket 23 in a clockwise direction, as viewed inFIG. 12, a pulling will be effected upon door carrier 30, and with alike pulling upon door carrier 28 by virtue of rotation of idlersprocket 34, thereby causing the associated doors 1,1 to be moved awayfrom each other toward the related jambs into open condition.Conversely, upon rotation of operator sprocket 23 in a counterclockwisedirection, as viewed in FIG. 12, a pulling will be effected upon doorcarrier 28 with a concomitant pulling of door carrier 30 toward idlersprocket 34 by rotation of the latter thereby causing doors 1,1 to bemoved into closed condition.

Each door carrier 28,30 is of relatively heavy gage sturdy metal andhaving flat upstanding bodies, as at 37; carrier 28 being contourwisedistinguishable by virtue of the provision of bosses 26,36 forconvenient attachment to the upper courses of the belts 24,33. Eachcarrier 30,28 has a relatively widened base portion, as at 38 (see FIGS.13, 14) for extension downwardly through an elongated slot-like opening39 formed in the bottom wall of housing 6 which is substantiallycoextensive with said housing for permitting traverse therethrough ofsaid carriers 30,28 for door operation. Said base portions 38 ofcarriers 30,28 are suitably fixed to the upper rails 13 of the relateddoors 1,1, as

- through suitable fasteners and the like (not shown).

Each carrier 30, 28 is contoured upwardly of opening 39 at their endsproximate the related jambs 4,4 in a stepped manner, as indicatedgenerally at 40,41, respectively, to avoid interferring contact withsprockets 23,24, respectively, when said carriers 30,28 are in door-openposition.

Each carrier rotatably mounts a pair of longitudinally, spaced-apartsupport rollers 42 being formed of wear resistant material and having agrooved periphery 43 for engaging a track 44, convex in cross section,and integral with an extruded bracket 45 in its lower end portion, saidlatter being suitably mounted within housing 6 but preferably in areadily detachable manner for ease of replacement and repair. Thus,rollers 42 effec-.

tively support the associated doors 1,1. Each carrier 30,28 alsorotatably mounts a control roller 46 having a slightly convex peripheralsurface, as at 47, for engaging in its upper portion the complementaryconcave under face of an abutment 48 also integral with bracket 45 andin vertically spaced, substantially registering relationship with track44. Thus, the engagement of roller 46 and abutment 47 acts as a limitagainst upwardly shifting of doors 1,1 so as to prevent same fromundesired vertical movement when power is applied for door operation.Each of rollers 42,46 of carriers 30,28 are mounted for limited verticaladjustment, as by means broadly indicated at 49, so that the properdisposition of doors 1,1 may be at all times maintained through thesimple expedient of regulating the adjusting means 49 and with rollers46 being equally readily controlled.

Provided within header housing 6 is an electrical control box E forreceiving the various electrical components, such as rectifiers, relays,resistors, transformers and the like, there being connection, as by aconductor 51, to the actuating switch device and a conductor 52 forconnection to the convenient source of electrical energy. Said controlbox E is also connected to motor M as through a conductor 53.

Turning now to FIG. 9, it will be seen that motor drive shaft 21 mountson its end within gear box B a driving bevel gear 54 meshing with adriven bevel gear 55 fixed upon a shaft 55 axially perpendicular todrive shaft 21 and journalled at its ends within bearings 56,57 providedin the opposed side walls 58,59, respectively, of box B. Carried uponshaft 55, substantially centrally thereof, is a gear 60 which mesheswith a pinion 61 keyed or otherwise mounted upon a shaft 62 axiallyparallel with shaft 55 and similarly journalled at its ends withinbearings 63,54 provided in gear box walls 58,59, respectively. On theend portion of shaft 62 proximate wall 58 there is carried a gear 65engaging a relatively enlarged pinion 66 secured on shaft 22 which isaxially parallel to shaft 55' and 62. Shaft 22 is journalled at its endsin bearings 67,67, provided in gear box walls 58,59, respectively, andprojecting outwardly of wall 58 to provide an extension or take-off formounting thereon of operator sprocket 23 as above described.Accordingly, it will be seen that gear train G comprises bevel gears54,55, and gears 60, 61, 65 and 66 whereby operator sprocket 23 may berotated through operation of drive shaft 21 for causing rectilinearmotion of door carriers 30,28 by means of transmission belts 24,33.

Also provided within gear box B is a second gear train, indicatedgenerally G, which constitutes a gear 68 fixed upon shaft 22 meshingwith a relatively enlarged gear 69 carried upon a shaft 70, axiallyparallel to shaft 22 and journalled at its ends in bearings 71,72 formedin gear box walls 58,59, respectively. Also fixed on shaft 70 on theside of gear 69 proximate bearing 71 is a driving gear 73 meshing with arelatively diametrically enlarged gear 74 carried on a shaft 75journalled at its ends in bearings 76,77 formed in a lateral extensionof wall 58, as indicated 58 and wall 59.

Fixed upon shaft 75 between gear 74 and wall extension 58 is a prewoundcompression spring 78 of spiral character, being concentric with shaft75 and having its inner end 79 accepted within a radial slot 80 formedin a collar 81 rigid with shaft 75. The outer end 82 of spring 78 issuitably anchored about a finger 83 formed on the inner face of wall 58and projecting inwardly thereof. It will thus be seen that gear train Gis constituted of gears 68, 69, 73, 74 which cause a winding orstressing of spring 78 during operation of motor M with consequentrotation of drive shaft 21. Thus, as will be shown hereinbelow, duringdoor opening action, spring 78 will be stressed for energy storage.

Shaft in its end portion remote from spring 78 extends beyond gear box59 and on such projecting portion mounts a pair of plate cams 84,85 eachhaving operating edges 84, 85 for engagement by cam followers 86,87,respectively, provided at the ends of control arms 88,89 ofmicroswitches 90,91, respectively, which latter are each connected as bya cable 92 to control box E for purposes presently appearing.

Referring to FIGS. 6, 7 and 20, idler sprocket 34 is carried upon a stubshaft r journalled within an elongated bearing block 93 having atransversely extending, substantially centrally located internallythreaded bore 94 within which is engaged the inner end portion of amounting screw 95; the opposite end of which extends through an opening96 in a depending flange 97 of a channel-shaped mounting bracket 98,which latter includes a flange 97 parallel to flange 97; said flangesbeing presented transversely of housing 6. Screw 95 is engaged at itsouter end, beyond flange 97, by a cap screw m, there being, if desired,a gasket for enhancing the securement. Flanges 97,97 have alignedopenings s, t, and s, t, respectively, through which extend smoothstemmed bolts w, w, respectively; the same also passing freely throughrelatively enlarged openings x,x, respectively, in bearing block 93. Attheir projecting ends bolts w,w are secured to nuts, as at 100, formaintenance in position. Encirclingly disposed about each bolt w,w is acompression spring 99,99 which bear at one end against the inwardlydirected face of flange 97 and at their other end against theconfronting face of bearing block 93. Said springs 99,99 are preset andserve to permit of relative movement of bearing block 93 with respect tobolts w,w for assuring of appropriate tension upon the belt about idlersprocket 34. It will thus be seen that opening 96 is smooth surfaced sothat screw 95 may move relatively therethrough under spring pressure.Bracket 98 is suspended from a support 104 suitably secured to the topwall of housing 6, there being screws 105 for effecting securementbetween mating surfaces of bracket 98 and support 104. It should benoted that timing belts 24,33 being, as indicated, preferably of moldedrubber, are probided with teeth, as indicated at 106, for engagementwithin complementary recesses 107 provided in the periphery of sprockets23,34 so that slipping is eliminated and wherefore the horizontalmovement of the courses of both belts 24,33 will be equal to therotating speed of the operator sprocket.

In order to stabilize doors 1,1 against inadvertent vertical tilting,there is provided at the lower, normally screen-presented end ofvertical rails 11 a bracket 108 having a flange 109 supporting normallyoutwardly from the rail for extension into guideways 110,110 provided inthe bottom rails 9,9 of screen 7,7, respectively; said guideways 110,110' being coextensive with said rails 9,9. Carried upon the upper faceof flange 109 is a pair of offset guide rollers 111,112 adapted forrotation about vertical axes for respectively abutting the inner andouter side faces 113,114 of an inverted trackway formed interiorly ofthe said bottom rails 9,9. Thus, as doors 1,1 travel with respect to theproximate screen 7,7 the same are maintained by guide rollers 111,112against undesired tilting or shifting within a vertical plane and thusare maintained in appropriately aligned and stabilized condition.

From the foregoing the operation of system A should become quiteapparent. With doors 1,1 in closed condition (as shown in FIG. 1) thecontrol switch, such as, for instance, located in a floor mat, isactuated and whereby power is applied through control box E to motor Mwhereby the drive shaft 21 is rotated and operator sprocket 23 is causedto rotate by motion transmission through gear train G. Thereupon, belts24,33 will cause door carriers 30,28 to move away from each other towardthe respective proximate jambs 4,4 and thus effect door opening.However, at a predetermined point in the travel of said door carriers30,28 into position, the power is reduced for slowing the door openingspeed. Such power reduction is effected by predetermined disposition ofcam 84 so that relative travel along its operating edge 84 of camfollower 86 will effeet the appropriate action within control box Ethrough triggering of the associated micro switch 90. However, as longas the control switch, that is the one actuated by an individualutilizing system A, is in closed condition the doors 1,1 will remainopen. Accordingly, the present invention contemplates slowing the dooropening speed through power reduction at a predetermined juncture in thedoor opening movement which may be considered the back check part of thedrive so that there is actually provided a two speed opening. Obviously,the opening speeds are adjustable and changes in speed in the openingcycle is simply effected by adjusting of the appropriate cam 84.

During the door opening operation with consequent rotation of shaft 22,motion will also be transmitted through gear train G' for causing atight winding of spring 78 for compressing same and causing the storingof mechanical energy. In actual practice, the spring 78 also assists inslowing the door opening speed when the power is reduced.

Upon opening of the control switch, as by a person passing from theswitch mat or the like, power to motor M is cut off. Thereupon theenergy stored in spring 78 is released to cause shaft 22, by means ofgear train G, to rotate in the direction opposite to that in which itrotated under influence of motor drive shaft 21 for door opening,thereby causing door carriers 30,28 to move from open to closedposition. However, the speed of door closing is uniquely controlledsince by rotation of shaft 22 drive shaft 21 will be rotated, by meansof gear train G, in reverse relationship to that during door openingoperation resulting in rotation of the motor armature (not shown) so asto cause the motor to act as a dynamic brake. It is to be noted thatgear train G is designed to operate as a reducer in one direction, thatfor door opening, and as an increaser in the opposite direction, thatbeing for door closing. Accordingly, motor M becomes a generatorcreating a brake resistance between its armature and the permanentmagnet field. The motor armature is connected to a closed electricalcircuit (not shown) which includes two variable resistors (not shown) sothat the closing speed may be increased or decreased by appropriateadjustment of the said resistors.

The closing of doors 1,1 may thus be effected also in a two-speedarrangement with cam 85 being so adjusted that when its operating edge85' is engaged by cam follower 87 microswitch 91 can cause, as it were,a switching in of one resistor and a switching out of the other. Thus,by an increased amount of resistance the closing speed is relativelyincreased and by decreasing the resistance a decrease in the closingspeed is brought about. Thus, with the resistors appropriately set, theclosing sped may be suitably reduced at a predetermined juncture duringthe travel of doors 1,1 to closed condition, there being an initialclosing speed and a latching speed. When doors 1,1 are open manually, tobe described hereinbelow, such will control the closing speed as in thiscondition the armature circuit is operated independently of the powersupply. In view of the foregoing, it will be seen that in the dooropening operation, motor M serves as the motivating force, while in doorclosing operation spring 78 provides the requisite force.

The utilization of spring 78 provides a safer operating door andeliminates the need of recycle door edge switches which are oftenrequired for safety. Spring 78 maintains the doors in closed conditionand at the same time permit of manual swinging of the doors, to be shownbelow, in the event of emergency, such as power failure.

Doors 1,1 of system A may be adapted for what is termed breakawayoperation under emergency conditions, that is, to permit same to beswung about a vertical axis into open condition where the same are insubstantially planar perpendicular relationship to the adjacent screens8,8' as indicated in phantom lines in FIG. 2.

As shown in FIGS. 13 and 10, upper door rail 13 of each door 1,1 is oftwo part construction, having a top component 19 and a lower component20 which coop erate to define a compartment for receiving a linkagesystem, indicated generally at 121 for controlling the relative swingingof door 1,1 about hinges 18. There is carried upon the upper surface ofrail component 20, at its hinge remote end, a latch 122 for engaging alatch hook 123 in order to maintain the related door construction in aunitary manner for slideable movement. However, upon release of latch122 each door is adapted for free swinging under what are commonlyreferred to as panic conditions so that doors 1,1 may be opened in theevent of a power failure or other type of emergency and with suchswinging being effective regardless of the disposition of doors 1,1 withrespect to their reciprocal paths of sliding movement.

As shown in FIG. 11, latch 122 comprises a housing 123, as formed ofsteel or the like, having an axial bore 124 within which is disposed acompression spring 125 bearing at one end against a ball 126 partiallyexposed through the adjacent end of bore 124 for purposes presentlyappearing; and which spring 125, at its other end, abuts against theinner end face of an adjusting plug 127 threadedly engaged within acounterbore 128 formed at the ball remote end of housing 123. Thus, thepressure on ball 126 may be readily controlled by appropriate tighteningor loosening of plug 127. Extending endwise of housing 123', both aboveand below the ball bearing end are upper and lower flanges 129,129 whichserve as guides for accepting a cooperating tongue-like member 130formed on latch hook 123 and having a concave recess (not shown) forreceiving the exposed portion of ball 126 with the same being urgedthereagainst by spring 125 for maintaining rail components 19,20 inreliably engaged condition so that the related doors 1,1 are secureagainst inadvertent swingable movement during normal operation.

From the foregoing, it should be quite apparent that the presentinvention is readily adapted for systems of the type shown in FIGS. 3and 4 which comprehend but a single sliding door as at 101, whereinobviously a single door carrier would be required. Also single doormodels are easily equipped with the breakaway safety feature abovedescribed in conjunction with doors 1,1, with the operation effected bysuch feature being indicated in FIG. 4.

Having described my invention, what I claim and desire to obtain byLetters Patent is:

1. A sliding door entrance system comprising a door frame having sidejambs and a header defining a door opening, said header having acompartment, a door for disposition planarwise parallel to said dooropening for normal closing relationship thereto, door suspension meansprovided in said header compartment comprising a door carrier having abody with a lower portion engaged to the upper end of the door forsuspension of the latter; a prime mover having a drive shaft, motiontransmission means comprising an operator sprocket, an idler sprocket,belt means trained about said operator sprocket and said idler sprocket,said belt means being engaged to said door carrier body a first geartrain operatively connecting said drive shaft and said operatorsprocket, a spring provided in said header compartment, and a secondgear train operatively connecting said spring and head operator sprocketwhereby when the latter is driven through said first gear train, saidspring will be stressed.

2. A sliding door entrance system as defined in claim 1 and furthercharacterized by said first gear train being adapted to effect a speedreduction from said drive shaft to said operator sprocket.

3. A sliding door entrance system as defined in claim 1 and furthercharacterized by said second gear train being adapted so that uponrelease of energy stored in said spring during stressing, said operatorsprocket will be caused to rotate in a direction opposite to that whenrotated by said first gear train for effecting travel of said doorcarrier for causing said door carrier to return to door closedcondition.

4. A sliding door entrance system as defined in claim 3 and furthercharacterized by means altering the angular speed of said operatorsprocket at a predetermined juncture prime mover driven operation andspringdriven operation for providing multi-speed dooropening anddoor-closing.

5. A sliding door entrance system as defined in claim 4 and furthercharacterized by said means altering the angular speed comprising cammeans operatively connected to said second gear train and controlelements having cam followers engageable by said cam means.

6. A sliding door entrance system as defined in claim 1 and furthercharacterized by said door comprising a vertical rail consisting of afirst and second components hingedly engaged to each other, latch meanscarried by said door for maintaining said first and second components innormal coplanar relationship, said latch means being adapted for openingaction to permit of swinging of said door about said hinges.

7. A sliding door entrance system as defined in claim 1 and furthercharacterized by means guiding said carrier for traverse of said headercompartment comprising a trackway provided in said compartment andextending axially parallel therewith, and support rollers mounted onsaid carrier body and engaging said trackway.

8. A sliding door entrance system as defined in claim 7 and furthercharacterized by an elongated abutment member disposed in said headercompartment in elevated relationship to said trackway and a limit rollercarried on said carrier for engaging said abutment to restrict verticaldisplacement of said carrier.

9. A sliding door entrance system as defined in claim 1 and furthercharacterized by means for adjusting said idler sprocket for maintainingtension upon the belt means trained thereabout.

10. A sliding door entrance system as defined in claim 1 and furthercharacterized by remote control means connected to said prime moverwhereby upon actuation of said control means said operator sprocket willbe rotated in one direction by means of said first gear train and saiddrive shaft and upon deactuation of said control means said operatorsprocket will be rotated in the opposite direction by means of saidspring and said second gear train causing said prime mover drive shaftto rotate in the opposite direction to cause said prime mover to act asa dynamic brake.

11, A sliding door entrance system as defined in claim 10 and furthercharacterized by a normally driven shaft provided in said headercompartment, said spring being mounted upon said driven shaft, gearmeans operatively connecting said second gear train and said drivenshaft whereby upon deactuation of said control means said driven shaftwill be rotated under influence of the release of energy by the springfor causing said operator sprocket to rotate in the direction oppositeto that caused upon actuation of said control means.

P051050 4 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3,834,081 Dated September 1 0, 974

Inventor) John c. Catlett It is certified that error appears in-theabove-identified patent and that said Letters Patent are herebyeorrected as shown below:

' Column 9, Claim 4, Line 49, after "juncture" insert -during y Signed and eeeled this 19th day of November 1974.

QSEAL) fi ttestz V MCCOY M. GIBSON JR. c. MARSHALL DANN AttestingOfficer Commissioner of Patents

1. A sliding door entrance system comprising a door frame having sidejambs and a header defining a door opening, said header having acompartment, a door for disposition planarwise parallel to said dooropening for normal closing relationship thereto, door suspension meansprovided in said header compartment comprising a door carrier having abody with a lower portion engaged to the upper end of the door forsuspension of the latter; a prime mover having a drive shaft, motiontransmission means comprising an operator sprocket, an idler sprocket,belt means trained about said operator sprocket and said idler sprocket,said belt means being engaged to said door carrier body a first geartrain operatively connecting said drive shaft and said operatorsprocket, a spring provided in said header compartment, and a secondgear train operatively connecting said spring and head operator sprocketwhereby when the latter is driven through said first gear train, saidspring will be stressed.
 2. A sliding door entrance system as defined inclaim 1 and further characterized by said first gear train being adaptedto effect a speed reduction from said drive shaft to said operatorsprocket.
 3. A sliding door entrance system as defined in claim 1 andfurther characterized by said second gear train being adapted so thatupon release of energy stored in said spring during stressing, saidoperator sprocket will be caused to rotate in a direction opposite tothat when rotated by said first gear train for effecting travel of saiddoor carrier for causing said door carrier to return to door closedcondition.
 4. A sliding door entrance system as defined in claim 3 andfurther characterized by means altering the angular speed of saidoperator sprocket at a predetermined juncture prime mover drivenoperation and spring-driven operation for providing multi-speeddoor-opening and door-closing.
 5. A sliding door entrance system asdefined in claim 4 and further characterized by said means altering theangular speed comprising cam means operatively connected to said secondgear train and control elements having cam followers engageable by saidcam means.
 6. A sliding door entrance system as defined in claim 1 andfurther characterized by said door comprising a vertical rail consistingof a first and second components hingedly engaged to each other, latchmeans carried by said door for maintaining said first and secondcomponents in normal coplanar relationship, said latch means beingadapted for opening action to permit of swinging of said door about saidhinges.
 7. A sliding door entrance system as defined in claim 1 andfurther characterized by means guiding said carrier for traverse of saidheader compartment comprising a trackway provided in said compartmentand extending axially parallel therewith, and support rollers mounted onsaid carrier body and engaging said trackway.
 8. A sliding door entrancesystem as defined in claim 7 and further characterized by an elongatedabutment member disposed in said header compartment in elevatedrelationship to said trackway and a limit roller carried on said carrierfor engaging said abutment to restrict vertical displacement of saidcarrier.
 9. A sliding door entrance system as defined in claim 1 andfurther characterized by means for adjusting said idler sprocket formaintaining tension upon the belt means trained thereabout.
 10. Asliding door entrance system as defined in claim 1 and furthercharacterized by remote control means connected to said prime moverwhereby upon actuation of said control means said operator sprocket willbe rotated in one direction by means of said first gear train and saiddrive shaft and upon deactuation of said control means said operatorsprocket will be rotated in the opposite direction by means of saidspring and said second gear train causing said prime mover drive shaftto rotate in the opposite direction to cause said prime mover to act asa dynamic brake.
 11. A sliding door entrance system as defined in claim10 and further characterized by a normally driven shaft provided in saidheader compartment, said spring being mounted upon said driven shaft,gear means operatively connecting said second gear train and said drivenshaft whereby upon deactuation of said control means said driven shaftwill be rotated under influence of the release of energy by the springfor causing said operator sprocket to rotate in the direction oppositeto that caused upon actuation of said control means.